Rossia is a genus of 10 species of benthicbobtail squid in the family Sepioidae found in all oceans. They live at depths greater than 50 m (164 ft) and can grow up to 9 cm (3.5 in.) in mantle length.[1] This genus was first discovered in 1832 by Sir John Ross and his nephew James Clark Ross in the Arctic Seas, showing a resemblance to another genus under the same family, Sepiola. After returning from their expedition, Sir Richard Owen officially classified Rossia to be a new genus, naming it after Sir John and James Clark Ross.[2]
Description
Rossia are categorized under the subfamily Rossiinae, which are identified by their short mantles and lack of ventral shield due to the unextended anterior ventral edge of the mantle.[3]
Rossia are distinguished by their dome-shaped mantles. which are not fused to their head.[1] They are shorter in length compared to many other bobtail squid, with mantle length varying from 1.4 cm (0.5 in) to 9 cm (3.5 in). Males do not grow to be as large as females.[1]
Each squid under genus Rossia have broadly separated fins with free anterior and posterior lobes.[4] Its tentacular club is expanded, with club suckers in series of 6 to 12 and no enlarged suckers are found on the lateral arms.[3] They lack photophores, but do possess functioning ink sacs. They also have small internal, chitinous pens.[1][5]
Distribution and habitat
Rossia are distributed throughout marine, benthic habitats worldwide. Most are commonly found in sandy or muddy bottoms on the seafloor. There is currently an insufficient amount of information to know the conservation status of Rossia.
Coast of Southern Florida, USA in the Strait of Florida.
Behavior
Rossia pacifica seen buried in the sand to hide from predators.
Rossia commonly bury themselves in sand by excavating a hole from underneath them by forcefully blowing water out of their siphon and throwing sand over their mantle with their arms. When predators are near, they release ink and jet themselves out of the sand, allowing for escape.[8]
Feeding habits
For species that have been studied, Rossia's diet consists of shrimps and prawns, but they have sharp and hardened beak which allows them to consume small crabs, along with fish and other cephalopods. They often use two tentacles to grasp their prey.
Reproduction and development
Males perform a variety of acts to attract potential females partners for reproduction. Rossia commonly reproduce by internal fertilization. During mating, the male inserts the hectocotlyus into the mantle cavity of the female where fertilization takes place.[9]
Spawning takes place year round, where small egg masses are found on seaweed or smooth objects on the ocean floor. Male and female adults often die shortly after mating.[10]
Egg cases have a thick, dense outer layer to protect the embryos, and are an average of 10 mm in diameter; however, the egg does not expand with development, and the embryo grows inside the casing.[11] When the egg masses of Rossia are ready to hatch, they push the tip of the mantle against the casing to break it, followed by the rest of its body.[12]
References
^ abcdefghijkJereb, P; Roper, C.F.E. "Cephalopods of the World". FAO Species Catalogue for Fishery Purposes No. 4. 1: 183–187. ISSN1020-8682.
^Ruppert, Edward E.; Fox, Richard S.; Barnes, Robert D. (2004). Invertebrate Zoology: a function evolutionary approach. Belmont, CA: Thomson-Brooks/Cole. pp. 360–367.
^Rodrigues, Marcelo; Guerra, Angel; Garci, Manuel E.; Troncoso, Jesus Souza. "Mating Behavior of the Atlantic Bobtail Squid (Sepiola Atlantica (Cephalopoda: Sepiodidae)". Vie et Milieu- Life and Environment. 59: 271–275.
